Steam-boiler



(No Model.)

N. P. STEVENS.

STEAM BOILER. No, 270,915. Patented Jan.23,1883.-

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N PETERS. Phclwulhngnphnr. Washington. I]. C

UNITE STATES PATENT QFFICE.

NATHAN P. STEVENS, OF CONCORD, NEW HAMPSHIRE.

STEAM-BOILER.

SPECIFICATION forming part of Letters Patent No. 270,915, dated January23, 1883.

Application filed May23,1882. (No model.)

To all whom it may concern:

Be it known that I, NATHAN P. STEVENS, of Concord, in the county ofMerrimack, of the State of New Hampshire, have invented a new and usefulImprovementin Steam-Boilers; and

I do hereby declare the same to be described in the followingspecification, and represented in the accompanying drawing, which is alongitudinal-section of a boiler of my improved kind, the nature of myinvention being defined in the claim hereinafter presented.

I would remark that although I have represented in the drawing a boilerfor a locomotive steam-engine, a boiler for a stationary engine may beconstructed with my improvement.

In such drawing, A represents the water and steam chamber of alocomotive steam-engine boiler, such being surmounted at its middle witha steam-receiving drum, B. .The firechamber shown at (l is at the middleof such water and steam chamber A, and extends out of and below such,and where extending below it is surrounded by an extension, D, of theboiler. The grate of such fire chamber is shown at a. There should beover such grate a suitable opening for the admission of fuel to thechamber, which opening should be provided with a door or doors. From thefirechamber, at its upper part, there are extended in oppositedirections two stacks of fire-tubes, I), each of which opens at theouter end of its tubes into one oftwo smoke boxes or chambers, D,arranged as shown, each of them being provided with a chimney, E. Inadvance of one of the said smoke-chambers is a supplementary chamber,F,into which the exhaust-steam from the cylinder or cylinders of theengine is to be led by a suitable conduit or conduits. From the saidsupplementary chamber blast-pipes G H are led into the lower parts ofthe two chimneys,each ofsuchblast-pipes,atits mouth, being provided witha valve or damper, e, for regulating the flow of steam into such pipe.The supplementary chamber 'E being common to both stacks, there is anequal flow through the blast-pipes G H, which produces an equal draftand keeps both portions of the boiler at an even temperature. From thedome one or more pipes, j, lead steam to the valve-chests of thecylinders.

From the above it will be seen that the smoke and gases generated in thefire-place will pass out of such in opposite directions through the twostacks of flue-tubes, and from them will flow into the two smoke boxesor chambers and escape by their chimneys, in which case each stack ofpipes may be very short in comparison to what would be required werethere to be to the boiler but one stack, one smoke box or chamber, andone chimney, as locomotive-engine boilers are usually constructed.Byhaving the pipes so diminished in length they are much easier cleanedof deposits, and, besides, advantages are otherwise gained by them.

The supplementary chamber is to effect a uniform or approximatelyuniform blast of 'steam in each of the chimneys, and not an intermittentone,as would follow without such a chamber; The waste steam entering thesupplementary chamber can expand therein, and will be driven therefrominto the chimney in uniform or approximately uniform currents, wherebythe draft of the furnace will be rendered substantially uniform, withlittle, if any, danger of the coalsor fuel being sucked into thetube-stacks.

With the dampers or valves to the two blastpipes the blast of either canbe regulated in quantity, as occasion may require/to effect uniformityof draft through the two stacks of fluetubes.

In my improved boiler I have but one fire place or chamber tothe twostacks of fluetubes leading in opposite directions. out of it, andthrough the water-chamber to the smokechambers, such being decidedlyadvantageous over separate fire-chambers to the two stacks, for with thesingle fire place, the exhaust-steam chamberF, and its blast-pipes andtheir valves, the smoke and heat can be directed through eitherof'thestacks, or caused to flow equally or unequally through both, as occasionmay require. Furthermore, it will be seen that the said fire-place iswholly within the water-space of the boiler, so that the crown-sheet ortop of.

the fire-place is covered by the water when in the boiler. It will alsobe seen that the fireplace is not extended underneath either of thestacks of flue-tubes, but is directly between them and projects belowthem, all of which is avery advantageous construction of the boiler,provided with the steam-exhaust chamber, the two smoke-boxes, and theirchimneys, as explained.

1 am aware that double boilers are old, and that it has been proposed toexhaust through their smoke-chambers into one or two chimneys. I am alsoaware that a boiler has been devised having an outside jacket, thusforming a double boiler for the purpose of utilizing the heat ofexhaust-steam to add to the temperature of the water in the boiler. Inthis latter construction the steam passes between the jacket and boiler,through the lower tubes of the latter, into a chamber provided with anadjustable valve which only lets the steam out under certain conditions,and after it has lost nearly all of its valuable heat. My invention isdifferent from these constructions. In my device the steam passesdirectly from the cylinder into the supplemental chamber F, which thusforms a reservoir for the exhaust-steam. From this chamber the steam -isconducted directly into the chimneys by the pipes G and H in an activecondition and calculated to materially assist the draft. In this way thesteam is utilized in an efficient manner, and as the chamber F is commonto both chimneys the same draft'is maintained on both sides of the fire,equalizing the temperature. I Having described my invention, what Iclaim The double boiler A, having the fire-tubes b b, and chimneys E E,in combination with the supplementalchamber F, common to both chimneys,and the pipes G H, leading from this chamber to the chimneys, andprovided with the valves 0, as set forth.

NATHAN P. STEVENS.

Witnesses:

M. P. FOSTER, A; B. GRoss.

